Contouring tracer



4 Sheets-Sheet 2 ATTORNEY.

Jun 15 1926;`

Y J. c. sHAw coNToURNG TRAGER Filed Jan, 22. 1924 .W .W NK

8. 8 ,m w m. M. W W N `lune l5 1926.

J. c. sHAw CONTOURING TRACER Filed Janj. 2`2, 1924 4 Sheets-She'et 5 INV NToR. C

'PatentedJune l5, 192.6. l ,UNITED-STATES 1,588,856. PATENT OFFICE.

JOHN c. a'nAW, or BROOKLYN, NEW YORK, AssIGNon To KELLER MECHANICAL EN- GINEEBING COEPOBATIION, or BROOKLYN, NEW `YORK, A conronA'rIoN or NEW YORK.

.Application led January 22, 1924. Serial No. 687,758.

My invention relates more articularly the electro-magnetic control o machine tools, in which feeds are provided for feeding the work in two rectilinear directions at rightI In my previous application, Ser. No."

604,923, filed December 4, 1922, there is described one form of contouring tracer,

which, While giving satisfactory results for l some classes of work, does not meet all of the requirements and, therefore, one object of. my improved contouring tracer is to in-l crease the sensitiveness of the control and to vprovide a satisfactory interlocking mechanism, whereby excessive 'feed motion in one direction 'or the other is adapted through the interlocking rect feed circult of the. other -arm,:and Simultaneously reverse the feed controlled by the first arm. p

Another object is to reduce the number'of -cont-act carrying arms to a minimum and adjust the-leverage to reduce the movement I of the contacts and thereby increase the sen- 'sitiveness of the control, so that the contacts controlling the feeds may be operated by ex-- -cessively small movements of the tracer -he'ad'andthe interlocking device is so coduced in the work.` v

-gn the accompanying drawings, I have illustratedy the one form vof `my improved 'contourin'g tracer,l ltogether' with a slight i .jmodiication, Fig1 1 showsa front elevation of the tracer; Fig. 2 shows a vertical longitud'nal section on the line 2.-2 -of Fig. 1; '2 Fi 3 shows a horizontal longitudinal section, in part broken away, :on the line 3-3 (ml'lch enlarged) certain steps in the method gofoperation; Fi 5 represents a diagram? ,L reumatislay-01111 0 the wiring connections; Figs.6"'to' 14 areY diagrams for illust-rating 5. the operation of the. device; and Figs. 15

mechanism to break the di,

ofFig. 1; Fig.l 4 is -a diagram representing S -CONTOURING TRACEB.

and '16 show a modification of the interlock x mechanism. f

Referring to the drawings, the tracer body comprlses a head 1 in whichr a tubular body portion 2 is secured, and through the center 00 of both x the.l head and tubular portion a tracer or spindle 3 extends. The outer end of the tubular portion 2 is counterbored and fitted with a ball socket bearing ringY 4, i' which is held in place by a thimble 5, screw 05 threaded into the end of the tube 2, (Fig.y 3) The body of the tracer spindlel 3 is provided with a spherical segment 6 in the form of a vcollar secured in place by a suitable nut 7 so as to form auniversal bearingwith the .ball socket 4, for the tracer spindle. The walls ofthe thimble 5 may be thick enou h to overhang the collar 6 to prevent wit drawal lof the tracer spindle from the tubular body ortion 2.` The Outer end of the ytracer spind e 3 extends beyond the end of the body portion 2 and carries a tracer head8," which may bepreferably secured thereto by a nut 9, so that the h ad 8 may be removably attached to the tra er spindle, thereby 8.0 allowing for the interchange of tracer points or heads of different sizes. 'The inner end 10 of the tracer spindle extends through thel head 1 and terminates in a button 11 adapted toengage and operate contact carrying arms as hereinafter explained.

I Since thel size of the'tracer head 8 may be variedfjitxwill be understood that the balance of the tracer spin`dle, as a whole, may

lvary and for this reason, it is preferable to -lprovide means for accurately balancing the spindle when in use. f tubular plug 12 is preferably linserted on the For this purpose, a

undersideof thel forward end ofthe tubular vbody portion 2, as shown in Fig. 2 of the 95 drawings, and this plug contains a movable solid plug or feeler 13, engaging the underside Of the end 10 of the tracer spindle. spring 14 is inserted between the lower endv .of the plug 13 and a screw 15 threaded into 10 the lower end ofthe tubular plug 12. It will thus be seen t at by adjusting the screw i 15; the pressure of he spring 14 can be regulated to p roperlyl balance the tracer spindle 3;.10 and a lock nut 16 will hold` the screw 105 in proper adjustment,

As more particularly shown i'n Figs. 2 and 3 of* the drawings, it will be4 seen that the head 1 of the tracer body'is preferably made up of a recessed casting, the forward no end of which is bored out at 17 to receive a rotatable contact carrying block 18. The block 18 may be of any suitable insulating material and is preferably annular in form and mounted upon a tubular hub 19, which is rotatably mounted in a bearing formed in an inwardly projecting flange 20 of the head 1. A bearing and spacing collar 21 is preferably mounted on the tubular hub 19 and may be utilized to hold ,the contact carrying block 18 in'place, while its opposite face forms a bearing against the face of the counter bore 17 and llange'20. The other face of the flange 20 serves as a thrust bearing for an annular bevel gear 22, which is secured to the end of the hub 19 by suitable screws 23.

Referring to Fig. 3, it will be seen that the annular bevel gear 22 is engaged by a bevel pinion 24, secured to the end of shaft 25 extending laterally through a tube 26 vprojecting from the side of the head 1. The tube 26 is held in place in the headsl by a suitable screw as at 27 and the outer end of the tube is provided with a housing 28, secured thereto by a screw 29. .The shaft 25 extends into the housing 28 and the inner end thereof is provided with a bevel pinion 30, engaging a bevel gear 31, which is secured to a short shaft 32 rotatably mounted transversely in the housing 28 as indicated in Fig. 3. The front wall of the housing 28 is preferably circular in form and provided with four index studs 33, while a pointer 34, secured to the shaft 32, is adapted to( cooperate therewith. A handle 35 yis preferably cast integral with thepointer 34, the handlenot only serving to adjust the pointer, but serving as an Iindex in itself, for it is spaced 45 from the pointer 34 and its relation to the index studs 33 is of importance as willrbe more fully explained hereinafter.

It will be seen that by rotating the shaft 32 by means of the handle 35,the contact carrying block 18 may be rotated with respect to the tracer head 1. The contact carrying block 18 is preferably provided with four commutator segments 36, which are located in the respective quadrants thereof, as more particularly indicated in the diagram in Fig. 5 of the drawings. The segments 36 are insulated from each other and spaced apart at their ends and may be referred to as A-B--C and D.rThe segments A and B are so connected up through suitable contacts and contact carrying arms as to control respectively, through suitable relays, the direct and reverse feed in one rectilinear direction and the segments C and D are similarly connected up to control the other feed in the same manner, so that in any position of rotation of the contact carrying block 18, the relation between the various segments will not be changed, but

the pairs of segments A, B, C and D may be brought into position to control the direct and reverse feed of the machine in two rectilinear directions, as previously referred to,

at each of the four index points or quad.

rants of rotation of the block 18 or pointer 34.

Of the commutator segments 36, the segments A and C (Fig. 5) are provided with inwardly projecting arms 37, preferably integral with Contact carrying posts 38, projecting through the contact carrying block 18, as more particularly shown i-n Figs. 1 and 2 of the drawings. Each contact post 3 8 carries a contact 39, cooperating with contacts 40, on the respective Contact carrying arms 41 and 42. The contact carrying arms 41 and 42 are pivotally mounted at 43 and 431'on studs orfscrews entering the hub 19, to which the contact carrying block 18 is secured, as previously pointed out. In this manner, it will be seen that the contact carrying arms 41 and 42 are grounded through the machine by the metallic connection through the hub 19.

The contact carrying block 18 supports two additional contact carrying posts 44, which, as shown in Fig. 2 of the drawings, are merely embedded in the insulating material of the contact carrying block 18, but each is provided with contacts 45 for cooperation with contacts 46 on the rear ends of the contact carrying arms 41 and 42, as more particularly shown in Figs. 1 and 5 of the drawings. The back contacts 46 of the arms 41 and 42 are preferably mounted upon short levers 47, pivoted at 48 to the respective arms, and are held. in operating position by means of light springs 49, extending between the heads 50 and the rear faces of the respective short levers 47.

'Springs 51 are connected from the respective arms 41 and 42 to studs 52 in the hub 19, thereby providing resilient means for holding the direct or forward contacts 39 and 40 closed under normal conditions.

The insulated ycontact posts 44 are connected by lead wires 53, through small electro-magnets 54 and lead 55 with posts at 56 extending upward from the respective cornmutator segments B and D, so that when the Iback contacts 45-46 of the contact carrying arms are closed, the respective magnets 54 will be energized. Cooperating with each of the magnets 54 is anarmature 57, pivoted at 58 to a plate 59, see'tired by screws 60 to the rotatable contact carrying block 18, as more particularly shown in Fig. 1 of the drawings. The armatures 57 are formed as levers, the short arms 61 of which extend un-l der the outer ends of the respective contact carrying arms 41 land 42. The magnets 54 are preferably secured to the supporting plate 59 by rearwardly extending brackets 62 pro- 1 vided 'with slots at 63, through which screws lili 64 are passed, thus providing means foradjusting the position of the ma y ets relative to the respective armatures 5` Also, cooperating Awith thearmatures 57, stopscrews are preferably mounted in posts 66 and adjusta le to limit the outward throw of the armatures 57. The adjustment of the magnets 54 and armatures 57 is such that when the magnets are` energized, the respective contact carrying arms 41 and 42 will be lifted or moved suiiiciently to break the contacts 39-40 for the direct-feed, but the `arms will not be moved far enough to close the back contacts 45-46. It wi lqbe seen, however, that the respective magnets 54 are energized-only by closing one or the other' `of the back contacts of the arms 41 and 42,

and when thev back contact of `one arm is closed, the forward` contact of the other arm will be broken by the attraction of the armature 57 of the corresponding electro-magnet 54. In thisV manner, it will be seen that.

the contact carrying arms are interlocked through the magnets so that excessive movement of .one of the contact carrying arms will result in breaking the direct contact of the other arm. n

Thus, incidentally, contactsy 45.--46 is closed, the corresponding circuit isv completed, Vnot only ythrough the corresponding electro-magnet 54 for break ing the direct contact of the other arm, but also through the associated commutator segment B or l)l to the magneticl clutch to operate the reverse feed of the machine .in one or the other of the'y feed directions,'fac' cordin'g toV which 'contact arm is .making the back contact and the relative angular position of the contact-carryin block 18.

`Arranged i around the ange' 67 .ofthe head 1 of the machine, in theres ective quad` rants thereof, are brushes 68 a apted to cooperate with. the commutator segments 36. The brushes 68 are preferably carbon cylinders, and springs 69, adjustably heldin place by screw caps 70, are adapted to hold the brushes in contact with the commutator segments 36 and the periphery of the contact carrying block 18, (see Fig. .1). The tubes 68a holding the. brushes 68 are insulated from the tracer head flange 67`and, vby suitable binding nuts each is connected to -a relay controlling one direction of .feed movement ofthe machine and, preferably, the

various circuits mav ybe connected up as.

shown inFig. 51of the drawings. The letters NS-W-E,'repres enting the points of the compass, are preferably' used and referred to in describing-the operation of the machine; north, meaning up feed; south,

down feed; east, feedV to the rightgand west.J

feedto the left.

Referring to. the wiring diagram as shown in Fig. 5 of the drawings, it will be *seen thatethe brush 68, marked N, is con! when oneliof'ythe back i -41 andv 42 will be closed, thereby completing" nected by a wire 71, with the magnets 72l viously pointed out, the contact carryingarms 41 and-42 are grounded throu h the hub 19. Likewise, the brush 68, mar ed S, is connected by wire 76 with relay magnet 77, (marked S) preferably opposite the re-J lay magnet 72 and anarmature 78 is located y ltherebetween for movement in response `to the eergization of either magnet. It will be seen that -when the circuit is completed through the relay magnet (N) 72, the Jarmature 78 will close the 110 volt circuit through the 4wire 79 to the magnetic clutch 80 (marked 'N), which perates the lnorth `or upward feed of the machine. The 110 volt circuit passing through the armature 78 passes throughwire 81 from the mainleadl 82'and the circuit from the magnetic clutch (N) 80l is completed through wire 83 to the main return lead 84.v Similarly, if the armature 78 is actuated by the magnet (S)A 77, connected with thebrush 68 marked S, the 110 volt circuit will `be connected through Wire 85 with' the magnetic l clutch 86 (marked S) controlling the downward feed movement. i

In like manner, the brushes the. letters Wand E -are connected res c-` tively to` relay magnets 87 (marked I), and 88 (marked E) by wires 89 and 90.4 The relay -magnets (E) 88and (W) 87' coo erate. with the single' armature ,91, which, like the armature 7 8,"is adapted to -move in one direction or the other, accord` ing to which 'magnet is-energized to close thegll() volt Fcircuit through wires 92 or 68 bearing 93 to-actuate one or the other of the mag-f` i pattern, the parts will occu y the posi- A tions shown in these views an the contacts 39 and 40 of both contact carrying arms the circuits through brushes 68 marked NI and W. In other words, the two feed; a

ias

clutches marked N and W will be closed and the direct feeds will be vup and to the left.

If l the rate of .feed is the. same in both diffrections, the resultant direction of motion will be at an-Qangle ofl 45 of northwest? bviously,if one 4of .the forward contacts -39---40 of one of the arms 41 or 42 is broken; l"

. ergized, while the relay magnet 87, marked the direction of feed will be either up or to the left according to which contact is broken. For instance, if the direct contact of the arm 41 through the brush N, as shown in Fig. 5l of the drawings, is broken, the relaymagnet N will be de-en- W, will remain energized and the direction of feedwill be solely toward, the left.

It will be understood that provision for rotating the contact carrying block 18, together with theycontact. carrying arms 41 and 42- and the interlocking mechanism, is,-

an important feature, in that it enables the operator to follow the work, that is, keep the button end 11 of tl1e`tracer spindle thrusting always toward the crotch between tlie contact carrying arms 41 and 42. Nevertheless, it frequently occurs, or may be desirable for the thrust to be exerted at a sharper angle relative to one or the othez.` ofthe contact carrying arms 41-42, and when this occurs, it is exceedingly important to prevent the button 11 from sliding lon itudinally of the contact carrying arm wit out lifting it sufficiently. This is effectively accomplished in the present device by means of a fixed member 96 secured by screws 97 to the face of the hub 19 of the rotatable unit, including the contact carrying block 18 and the contact carrying arms 41 and 42. As will be seen iii Fig. 1 of the drawings, the block 96` is preferably provided with a V-shaped end, so as to provide two points of engagement with the periphery of the button 11, when the latter is central of the rotating member. Obviously, there is just space enough between the button, when barely touching the `,fixed points of vthe block 96, 'for the forward contacts on the arms 41 and 42 to be closed by their respective springs 51. It will be seen, however, that by this arrangement, itis impossible for the button 11 of the tracer yspindle tol slide longitu-` dinally of either of the lcontact carrying arms, for any pressure in that direction will merely cause the button 11 to be cammed ofi' the point of stop 96 and thrust toward the corresponding contact carrying arm to, lift it further, thereby actuating the arm as it should be actuated without permitting longitudinal sliding movement with respect ing tracer embodying the electro-magnet interlocking mechanism will now be described, in connection with the diagrammatie views shown in Figs. 4 and .to 14 inclusive. It will be understood that my improvedcontouringtracer is designed to s be operated in connection with electro-magnetic clutches controlling the feeds in the two directions substantially as shown and described in my Patent No. 1,506,454 of land importance of my improved interlock contourlng tracer lies in the utility of the devlce for operating upon models or 4templates of extremely complicated contour,

as well as upon those of simple contour. In order to illustrate the operation in connection with a more or less complex job, attention is called -to the diagram in Fig. 4 of the drawings, where the steps of movement of the contouring tracer are shown enlarged or magnified many times. This illustration of the operation is more particularly adapted to show the action of the interlocking mechanism and how the tracer will follow a humpy or irregular job, without rotating the contact carrying block 18 and the associated contact carrying arms to the extent that ordinarily should be done, as explained later. In other words, this will explain how the tracer will work itself over a small hump in the contour. For instance, in Fig. 4, assume that the pointer 34 is in the position illustrated in Fig. 1 and the con- .tact carrying block and contact carrying arms are in theposition shown in Figs. 1 and 5 of the drawings. In this position, as previously stated, the direction of motion will be up and toward the left or northwest. The tracer will thenmove from position (1) to position (2) at an angle of 45, on the assumption that the feeds are equal in both directions. As soon as the tracer strikes the contour ofthe pattern at (2) the north or up feed will stop. Then the west feed will be interrupted and the arm 42, controlling the west feed will be thrown over far enough to close the back contacts 45-46 for the reverse or east feed and the tracer will be moved to Then the relay circuit through the back vcontact 45-46 and the relay 88E. is operating, it will be understood that the interlock magnet 54 is energized and, through the armature 57 and arm 61, will positively break the contact of the north feed. i

As soon as the tracer moves east to the point (3) the east' or reverse contact 45-46 will be broken and the north contact 39-40 of the arm 41 will be closed. The tracer will then move tol'position Here the operation will be again repeated, that is, closing the east contact and breaking the north contact and the tracer will move out to position This' operation will be repeated exceedingly rapidly and an indefinite number of times, while following up .the curve to the point (6). Here it will be --seen that the contact controlling the west feed through the relay 87W will be 'broken and the feed will he north or up to the,

moves away from the-contour far enoughl vto permit contacts 39--40 of the arm 42 to operate, the west rela 87 will again throw the magnetic clutch or the west feed-and themovement will be northwest to the point (8). Here again the west feed will be .d

illustrated in connection with the diagrams shown in Figs." 6 to 1'3. Assuming the model to have straight horizontal sides and a rounded end, it will be seen that if the machine is started, as shown in Fig. .6, with the pointer 34 on. the index 33, designated as NE, the direction of feed will be northeast, as indicated by the arrow crossingthe circle just below the model. Assoon as the tracer strikes the eriphery of the model, the north or up eed will be stopped by breaking of the'direct or forward contact of the contact carrying arm 42, while the feed toward the east (right) will continue until the tracer reaches the point A where the curve begins. kThen, as shown in Fig.

7, both the north and east contacts will operate intermittently to carry the tracer around the curve and preferably, the pointer 34 is moved to the position indicated iny p Fig. 7 and maintained practically parallel to a tangent to the curve at the 'point of contact of the tracer. Obviously, this does not change the two directions of feed, but

facilitates the action of the tracer spindle or button 11 on the contact carrying 'arms 41 and 42, by maintaining the resultant direction of feed at all times, substantially at 45 to each o vthe arms 41 and 42, thus lequalizing the effect of any movement of the tracer.

The north and east feed motions should be continued .until the tracer A reaches the point indicated in Fig. 8 0f the drawings. Then the handle35 should be moved ast the NE index to the position indicate in Fig. 8. This bringsinto action. the north and Iwest feed `controlL relays. Tlgis movement of the handle35 past the index NE, it will be understood, is necessary vf'orxas previously pointed out, the commutater segments 36 are spaced apart/and the'rela'tion between the handle 35 and the segments, as shown in Fig. 5 of thedraw-ings, is such that when the handle is'immediatel over one of the index points', the brus es 68 are on the insulating material of the contact carrying block 18 between the segments 36, therefore, these points. being dead points,

It is then necessary to ro-" both feeds will be cut out. If the handle 35 is -not moved beyond the dead point, as shown in Fig. 8, the tracer would continue in the northeastv direction, as indicated by the tangent line and arrow in Fig. 9 of'the rawings.

position shown in Fig. 8, the north and west feeds willbe in o eration simultaneouslyor alternately, wh1 e following the curve up tothe oint A in Fig. 10of the drawings, and ere again, if the handle and pointer are not moved, beyond the dead point, the tracer would continue in aline tangent to the curve in the northwest' direction. The handle 35 should, therefore, be moved to the' position shown in Fig. I1, after which the two feeds in operative control will be south and west. These" will 'continue to finish the curve 'tothe point A in Fig. 11 and, after the curve merges into the straight line at the upper side of the model, the south feed will be stopped by breaking of-the south contact andwest feed will continued until the tracer arrives at the point A in Fig. 12 of the drawings, The

handle 35 is then shifted to the index" SE as shown in Fig. 12 and the tracer will then follow the vertical line south, while the east feed is suppressed by lopening the east contact. When the tracer reaches the lower left hand corner of the model, as indlcated in Fig. 13 of the drawings, the handle again should be moved, so. as to brin the pointer 34 to the NE index, after whic the feed will be eastpwith the north feed suppressed by the north contact being held open. This will bring thetracer back to the starting point, as indicated in Fig. 6 of the drawings. v

When the model or pattern to be reproduced has an internal contour, the operatlons are substantially the same as Athose ldescribed for Figs. 6 to 13, except that,.as

' After the handle 35 has been movedto the I los never run oilI or out of contact with the contour of the pattern. Furthermore, when working on an internal contour, as illustrat-v ed 1n Fig. 14, 1t 1s preferable to work around the contour 1n clockwise direction, while, as

previously described, when operating on an j external contourf, as shown in Figs.;v 6- to 13,?.

it is preferred' to work around the .mod ei'l'l'go` and index dial counter-clockwise.. Therefore, the direction of feed on the lower''internal edge of the mdehas 'shown bythe.

arrow in Figi 14,'will be toward the-.fg ft, provided the a In this position thefsouth feed be supndle 35 is turned as it should I be, so that the polnteris' at'the SW index( pressed, while the 4'west feed. will vcontinuev until the tracer reaches the corner, when 1twill be stopped by the breakingof'the contact. The pointer 34 should thenbe turned to the index NW, after which the north feed will carry the tracer to the upper left corner. The pointer should then be turned to the index NE and the operation continued until the curve is reached, after which the tracer is worked around the curve, 'substantially as previously described.

It will be understood that the rate of feed in the two rectilinear directions should 42, as is required in the interlock mechanism previously described. Obviously, this construction permits tbe use of heavier springs 51, while, at the same time, providing rapid and easy operation of the rela-y contacts for effecting the-interlock. This has the advantage of providing a quick operating device, requiring less power.

While I have shown my improvedconbe the same for the best results, and it is^touring tracer in the preferred form, it will found in practice thatla feed of two (2) inches per minute gives satisfactory results and preferably the feed should not exceed 2% inches per minute. It will also be `understood that, when following a curve, the circuits are interrupted by breaking the contacts momentarily, so that, while the feed, as represented in magnified form in Fig. 4 of the drawings, produces a saw-tooth edge,

the interruptions are so rapid and theamount of feed prior to the interruptions is so small, that the teeth formed are really microscopic, therefore, the resultant is a substantially accurate reproduction of the curve of the contour.

. It is sometimes desirable to operate tbe tracer with rather heavy springs 51 holding down the respective contact carrying arms 41 and 42 and under these conditions, it is preferable to break the circuit through the contacts 39;;40, without lifting the re-v spective-contact carrying arms. With this in View, I have shown in Figs. 15 and 16 a modification of the interlock mechanism, in which the magnet 54 operates a relay circuit, thus removing the interlock mechanism from the infiuence of spiin 51.- Referring to Figs. 15 and 16, it will be seen that the electrical connections to the magnets 54 remain the same as previously described, but` instead of the lever armature 57-61, a simple relay armature 57a is pivoted at 58a, in position to cooperate with the magnet 54. T he free end of the armature 57a is provided with a contact point 100, which is adapted to cooperate with a contact 101 mounted upon an insulated post 102, the

' y latter being secured to the plate 59, as'shown in Fig. 15. A spring 103 is provided to normally hold the contacts 100-101 closed.

In providing for this change in the interlock, the bridge 37, as shown in Fig. 5, between the commutator bar 36 and the post 38 is removed and the associated commuta- -tor segment 30 is electrically connected to the armature 57a by the lead wire 104. The circuit' previously established through the bridge 37 is completed byI connecting the contact 101 on the post 102 with the post 38, by means of the lead wire 105. By this construction, it will be seen that the interlock'is effected through the relay armature i 57 by breaking the contacts 100--101 instead of breaking the contacts 39-40, thus avolding lifting the contact carrying lever be understood that for special machines, and in adapting the contouring tracer to various types of work, numerous modifications in .the specific details of construction may be required, and, therefore, I do not wish to be limited in the interpretation of the claims to the specific details shown, for various modifications ma be made therein without departing from t e spirit and scope f the invention. l

I claim 1,. In a contouring tracer, the combination with a tracer spindle, of a contact carrying head, a pair of contact carrying arms pivotally mounted` upon said head, and carrying contact on each side of the respective pivots, said arms extending at right angles to' eachfother and adapted to engage and be actuated by the end of said tracer.

2.4In a contouring tracer, the combination with a tracer spindle, of a contact carrying head, a pair of contact carrying arms pivotally mounted upon said head and extending at right angles vtoeach other, said arms being adapted to engage the end of said tracer spindle at points 90 apart, and direct and reversing contacts carried by each of said arms.

tion with a tracer spindle, of a contact carrying head, a pair of Contact carrying 'arms pivotally mounted on said head and extending at right angles to each other, said arms being adapted to engage the end of said tracer bar, a fixed member mounted on said block at an angle of 45 to each of said arms, said member being provided with points engaging said tracer spindle.

4. In a contouring tracer, the combination with a tracer spindle, of afcontact carryin block, rotatable about the axis of said spindle, a pair of contact carrying arms pivotally mounted upon said block and carrying contacts on each side of the respective pivots, said arms extending at right angles to each other and adapted to engage and be actuated by the end of said tracer spindle, and means for rotating said block. l

carrying block, rotatable about the axis of said spindle, a pair of contact carrying arms pivotally mounted upon said block and ex- 3. In a contouring tracer, the combina- I of said arms, and means for rotating said'l block. p d 6. I n a contouring tracer, the combination with a tracer spindle, of a' contact carrying block, rotatable about the axis of 10 said spindle, a pair of contact carrying? arms pivotally mounted on said block and extending at right angles -to eachother, Said arms being adapted to engage the end of said tracer spindle at points 90AU apart, a fixed member mounted on said block. atan angle of 45 to each other of said arms, said member being provided with points engagingsaid tracer spindle, and means for rotating said block.` 7. Ina contouring` tracer, the combination with a tracer spind1e,'of a contact carrying block, rotatable about the axis of said spindle, a pair of contact carrying arms mounted on said ,block at right angles to each other and adapted to be. engaged and. actuated by the end of said tracer spindle, electro-magnets su ported on said block for actuating each o said arms independently of said tracer spindle and means for rotating said 3 block. a l

' 8. The' contouring tracer, as claimed in claim 7, in which each of said contact carrying arms carries a back contactfor closing the circuit through the magnet actuating the other of said contact carrying arms. a 9. The contouring tracer, as 'claimed in claim 8, in which each of said contact carrying arms carries aforward and a back contact for controlling respectively direct and 0 Vreverse feed circuits, a'nd' the electro-magnet for actuating eachy arm is in series with ythe reverse feedicircuit of the other arm., 4 l v10. The system of electro-magnetic control of the feed of machine tools, in which4 5 magnetic clutches are provided for establishing direct and reverse feed in two rectilinear'directions at right angles to each other in the same plane, comprising a tracer spindle, the tracer end of whichis adapted to eirgage the contour of the model to be repro-2'.

duced, acontact carrying block mountedv for .rotation about the axis of saidl spindle, a

. pair of contact carryin arms mounted upon and rotatable with sai block, said armsbe.-

ing adapted to engage-the other end of the' tracer spindle, circuibconnections from said` contact carrying block ,lto said magnetic clutches for controlling the respective direct o tact carrying arms by movement of thetracer spindle',l and means ,for rotating said block.

11. The system ofy Vfeed control as claimed in vclaim 10, in which each/of saidcontact carryingarms carries a forward and a back contact for-the respective-direct and reverse and r verse feeds upon actuation of said confeed circuits, the circuits of the latter being each interlockedthrough electro-magnets to break the direct feed circuit of the other arm.

12. In a contouring tracer, the-combination with a body-portion, of a tracer spindle, supported therein for universal lateral move- -ment, one end of said tracer spindle being provided with a tracer head, for engagement with themodel or pattern to be reproduced, a pair of contact carrying arms pivotally mounted at rightangles to/each other, 1n position to engage the other end of said tracer spindle, each of said arms being pro-- vided with two contacts, one, on each side of the 4respectivepivots thereof, and a con'- tact carrying block supporting said arms and provided with contacts for cooperation with the contacts of the arms.

l13. The contouring tracer, as claimed in claim 12, in which said contact carrying` block is mounted on said body portion, for rotation about the axis of said tracer spindle and manual means isy provided for rotating saidblock.'

14. In a 4contouring tracer, theC combination with a tubular body portion, providedv with a lieadfat one end, a tracer spindle mounted in saidtubula'r bod for -universal lateral movement of the en s thereof one end of said spindle, projecting beyond the body portion, being rovided with a tracer for cooperation wit the contour of the model to be reproduced, a contact carrying block rotatably mounted in 'said head, a pair of contact carryin arms mounted on said block at right ang es to each otheigeach of said armscarrying two contacts adapted 5to cooperate withv contacts on said block, said arms enga `ng the other end of said vtracer spindle, w ereby movement of the latter is adapted to control .the making and breaking' of said contacts, a plurality of commutator segments mounted on the periphery of saidv block a-nd connected with the respective contacts carried by the block'and a correspond-- ing plurality of contact brushessupported in the head of said body member.

v15. The contouring tracer as claimed in claim 14,- in which two of said contacts cariis ried by the vblock are connected to their respective 'commutator segments throu h`electro-magnets, 4the 'armatures of which are adapted, when the magnets are energized, to

`break the Vrespective circuits through the.

other :two contacts.

16. Inra contouring tracer, the combinat tion with a body portion, of a tracer spindle mounted therein or universal movement of the ends thereon/a' contact carrying block rotatably mounted in said body portion,

manual .means for rotating said block, four commutator se ents in the periphery of said block, four rushes for engagement withi saijd coininutatorA segments, said brushes -being mounted on said body ortion and equally spaced around said blocllx), a corresponding number of contacts mounted on said block and connected with the respective segments, two of said contacts being connected to their segments through electro-magnets supported upon and rotatable with said block, a pair of contact carrying arms pivotally mounted upon said block, at right angles to each other, in position to be actuated by movement of l assieme said tracer spindle, each of said arms beingprovided withfront and back contacts for cooperation respectively withy the contacts on said block, the back contacts'of said arms closing the respective circuits through said 15 magnets, and armatures actuated by` said magnets for breaking the circuits through the front contacts of the respective arms.

JOHN C. SHAW.' 

